---
id: heatmap
title: 热力图
---

### 示例

```jsx live
function render(props) {
  const container = useRef(null);

  const dataUrl = useBaseUrl('/json/heatmap.json');

  const initChat = (map, option) => {
    const chart = new EChartsLayer(option, {
      hideOnMoving: true,
      hideOnZooming: true,
    });

    chart.appendTo(map);
  }

  const init = async () => {
    const map = new ol.Map({
      target: container.current,
      view: new ol.View({
        projection: 'EPSG:4326',
        zoom: 5,
        rotation: 0,
        center: [113.53450137499999, 34.44104525],
      }),
      layers: [
        new TileLayer({
          source: new XYZ({
            url: 'https://{a-c}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png',
          }),
        }),
      ],
    });

    const response = await fetch(dataUrl).then(res => res.json());

    const convertData = (data) => {
      const res = [];
      for (let i = 0; i < data.length; i++) {
        const geoCoord = response.coordinates[data[i].name];
        if (geoCoord) {
          res.push(geoCoord.concat(data[i].value));
        }
      }
      return res;
    };
    const option = {
      title: {
        text: '全国主要城市空气质量',
        subtext: 'data from PM25.in',
        sublink: 'http://www.pm25.in',
        left: 'center',
        textStyle: {
          color: '#fff',
        },
      },
      backgroundColor: 'transparent',
      visualMap: {
        min: 0,
        max: 500,
        splitNumber: 5,
        inRange: {
          color: ['#d94e5d', '#eac736', '#50a3ba'].reverse(),
        },
        textStyle: {
          color: '#fff',
        },
      },
      series: [{
        name: 'AQI',
        type: 'heatmap',
        data: convertData(response.attr),
      }],
    };

    initChat(map, option);

    function resize(target) {}

    return {
      resize,
    }
  }

  useEffect(() => {
    const { resize } = init();

    return () => {
    };
  }, []);

  return (
    <div className="live-wrap">
      <div ref={container} className="map-content" />
    </div>
  );
}
```
